jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1Allocator.cpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/g1Allocator.cpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/g1Allocator.cpp

Fri, 10 Oct 2014 15:51:58 +0200

author: tschatzl
date: Fri, 10 Oct 2014 15:51:58 +0200
changeset 7257: e7d0505c8a30
parent 7118: 227a9e5e4b4a
child 7647: 80ac3ee51955
permissions: -rw-r--r--

8059758: Footprint regressions with JDK-8038423
Summary: Changes in JDK-8038423 always initialize (zero out) virtual memory used for auxiliary data structures. This causes a footprint regression for G1 in startup benchmarks. This is because they do not touch that memory at all, so the operating system does not actually commit these pages. The fix is to, if the initialization value of the data structures matches the default value of just committed memory (=0), do not do anything.
Reviewed-by: jwilhelm, brutisso

 /*
  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "gc_implementation/g1/g1Allocator.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.hpp"
 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
 #include "gc_implementation/g1/heapRegion.inline.hpp"
 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
 void G1DefaultAllocator::init_mutator_alloc_region() {
   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
   _mutator_alloc_region.init();
 }
 void G1DefaultAllocator::release_mutator_alloc_region() {
   _mutator_alloc_region.release();
   assert(_mutator_alloc_region.get() == NULL, "post-condition");
 }
 void G1Allocator::reuse_retained_old_region(EvacuationInfo& evacuation_info,
                                             OldGCAllocRegion* old,
                                             HeapRegion** retained_old) {
   HeapRegion* retained_region = *retained_old;
   *retained_old = NULL;
   // We will discard the current GC alloc region if:
   // a) it's in the collection set (it can happen!),
   // b) it's already full (no point in using it),
   // c) it's empty (this means that it was emptied during
   // a cleanup and it should be on the free list now), or
   // d) it's humongous (this means that it was emptied
   // during a cleanup and was added to the free list, but
   // has been subsequently used to allocate a humongous
   // object that may be less than the region size).
   if (retained_region != NULL &&
       !retained_region->in_collection_set() &&
       !(retained_region->top() == retained_region->end()) &&
       !retained_region->is_empty() &&
       !retained_region->isHumongous()) {
     retained_region->record_top_and_timestamp();
     // The retained region was added to the old region set when it was
     // retired. We have to remove it now, since we don't allow regions
     // we allocate to in the region sets. We'll re-add it later, when
     // it's retired again.
     _g1h->_old_set.remove(retained_region);
     bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
     retained_region->note_start_of_copying(during_im);
     old->set(retained_region);
     _g1h->_hr_printer.reuse(retained_region);
     evacuation_info.set_alloc_regions_used_before(retained_region->used());
   }
 }
 void G1DefaultAllocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
   assert_at_safepoint(true /* should_be_vm_thread */);
   _survivor_gc_alloc_region.init();
   _old_gc_alloc_region.init();
   reuse_retained_old_region(evacuation_info,
                             &_old_gc_alloc_region,
                             &_retained_old_gc_alloc_region);
 }
 void G1DefaultAllocator::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
   AllocationContext_t context = AllocationContext::current();
   evacuation_info.set_allocation_regions(survivor_gc_alloc_region(context)->count() +
                                          old_gc_alloc_region(context)->count());
   survivor_gc_alloc_region(context)->release();
   // If we have an old GC alloc region to release, we'll save it in
   // _retained_old_gc_alloc_region. If we don't
   // _retained_old_gc_alloc_region will become NULL. This is what we
   // want either way so no reason to check explicitly for either
   // condition.
   _retained_old_gc_alloc_region = old_gc_alloc_region(context)->release();
   if (ResizePLAB) {
     _g1h->_survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
     _g1h->_old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
   }
 }
 void G1DefaultAllocator::abandon_gc_alloc_regions() {
   assert(survivor_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");
   assert(old_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");
   _retained_old_gc_alloc_region = NULL;
 }
 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
   ParGCAllocBuffer(gclab_word_size), _retired(true) { }
 HeapWord* G1ParGCAllocator::allocate_slow(GCAllocPurpose purpose, size_t word_sz, AllocationContext_t context) {
   HeapWord* obj = NULL;
   size_t gclab_word_size = _g1h->desired_plab_sz(purpose);
   if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
     G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose, context);
     add_to_alloc_buffer_waste(alloc_buf->words_remaining());
     alloc_buf->retire(false /* end_of_gc */, false /* retain */);
     HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size, context);
     if (buf == NULL) {
       return NULL; // Let caller handle allocation failure.
     }
     // Otherwise.
     alloc_buf->set_word_size(gclab_word_size);
     alloc_buf->set_buf(buf);
     obj = alloc_buf->allocate(word_sz);
     assert(obj != NULL, "buffer was definitely big enough...");
   } else {
     obj = _g1h->par_allocate_during_gc(purpose, word_sz, context);
   }
   return obj;
 }
 G1DefaultParGCAllocator::G1DefaultParGCAllocator(G1CollectedHeap* g1h) :
             G1ParGCAllocator(g1h),
             _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
             _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)) {
   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;
 }
 void G1DefaultParGCAllocator::retire_alloc_buffers() {
   for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
     size_t waste = _alloc_buffers[ap]->words_remaining();
     add_to_alloc_buffer_waste(waste);
     _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),
                                                true /* end_of_gc */,
                                                false /* retain */);
   }
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1Allocator.cpp@e7d0505c8a30 (annotated)

src/share/vm/gc_implementation/g1/g1Allocator.cpp